As of version 4.2.x, the EUM Server is not available for High Availability out of the box.
High Availability Controller deployment is available to help minimize disruptions caused by server or network failure, administrative downtime, and other interruptions. Those interested can view this overview of High Availability.
If you are interested in having your EUM Server run in High Availability, please contact your account representative and our professional services engineers to discuss the available options.